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Divestiture Transactions and Discontinued Operations - Additional Information (Detail) - USD ($)	3 Months Ended	8 Months Ended	12 Months Ended
	Jul. 31, 2013	Dec. 31, 2014	Dec. 31, 2015	Apr. 30, 2014	Apr. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of discontinued operations, net	$ (378,000)	$ 0	$ 0	$ (378,000)	$ 0
Divestiture transactions		(553,000)	(5,517,000)	7,455,000
Remaining divestiture costs		16,667,000	17,765,000	$ 17,612,000
Proceeds from sale of assets			5,335,000
BioFuels [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture transactions		$ (553,000)
BioFuels Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Undiscounted purchase consideration	$ 2,000,000
Undiscounted purchase consideration paid in installments	5 years
Maine Energy Facility [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Undiscounted purchase consideration					$ 6,650,000
Undiscounted purchase consideration paid in installments					21 years
Divestiture transactions			1,149,000
Remaining divestiture costs			0
Western Region [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received from sale of assets			872,000
Divestiture transactions			(590,000)
Western Region [Member] | Cares [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge			7,455,000
Casella-Altela Regional Environmental Services, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture transactions			$ (2,850,000)
Membership interest			51.00%
Proceeds from sale of assets			$ 3,500,000
Casella-Altela Regional Environmental Services, LLC [Member] | Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture transactions			(928,000)
Proceeds from sale of assets			$ 1,050,000
Altela, Inc. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Membership interest			49.00%

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